What causes population size variation of invaders? Resources and demography of Alliaria petiolata.
Hyatt, Laura*,1, Rodriguez, Rebecca1, Mann, Rajmeet1, 1 Rider University, Lawrenceville, NJ, USA
ABSTRACT- Information about how plants respond to seasonally changing resources enables us to understand patterns of population growth. Single resources may have contrasting impacts on different life history stages, enhancing survival and growth at one stage, and impairing it at another stage. In addition, different resources are likely to contribute to the success of different life history stages. This concept is especially important for understanding the success of exotic invasive species such as Alliaria petiolata. Growth, survival and fecundity of A. petiolata is being observed in 40 permanent field study plots along with soil N availability and pH to determine how these abiotic factors influence plant life history. We report on our findings about the role resources play in the first year of the life cycle and seed and fruit production. Increased availability of NH4+ was associated with increased leaf number and leaf number influenced percent survival, but had no measurable association with seed production. In contrast, soil pH and NO3- availability was significantly associated with increased seed and silique quantity per plant, but had no impact on seedling ecology. This was not due to covariation; we found no relationships between NO3-, NH4+ and pH. Thus, in A. petiolata, resource availability does not impact all life history stages in the same way. These findings highlight the necessity of exploring the diverse demographic impacts of changing resource availability especially as we consider control mechanisms for invading plants.
Key words: biological invasions, garlic mustard, demography
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